VITAMIN C - THE MASTER NUTRIENT
Preface | Foreword | Introduction | Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | Chapter 6 | Chapter 7 | Chapter 8 | Chapter 9 | Chapter 10 | Chapter 11 | Chapter 12 | Chapter 13 | Bibliography
Vitamin C and Ester-C Metabolism and Metabolites
VITAMIN C LITERACY
Before embarking upon an investigation into the therapeutic powers of Vitamin C, a summary of some of the technical language and constituents involved in the formulation of various products is provided which may prove useful to the consumer and professional alike.
Chemical formulae and biochemical pathways are not engraved in stone upon the brains of scientists, at least not upon that of the author. Even after many years and advanced courses in biochemistry, physiology, etc., these pathways fade from memory unless in constant use. And, with the incredibly rapid advances in knowledge occurring in science and medicine, much material may simply be new and not have been taught during one's formal training. These formulae are presented here as aids in understanding as well as a handy reference tool.
STRUCTURE AND BIOSYNTHESIS OF VITAMIN C
Vitamin C, also known as L-Ascorbic acid, L-xyloascorbic acid, 3-oxo-L-gulofuranolactone (enol form), L-3-ketothreohexuronic acid lactone and antisorbutic vitamin, has the chemical formula C6H8O6 and a molecular weight of 176.12. This 6-carbon molecule is structurally very similar to the sugar D-glucose (Fig. 1), a point of significance which will be addressed when considering the mode of action and mechanisms underlying Vitamin C's therapeutic effectiveness with diabetes and heart disease.
Humans, non-human primates, guinea pigs, the red-vented bulbul (an Asian bird), the Indian fruit-eating bat, rainbow trout and Coho salmon are the only animal species lacking the complete enzymatic machinery to synthesize Vitamin C. It has been shown that humans and guinea pigs lack the enzyme gulonolactone oxidase, which oxidizes l-gulonolactone to 2-keto-l-gulonolactone. This, then, is the 25-60 million year old evolutionary accident spoken of earlier which has deprived humans and these other animals of their ability to synthesize their own Vitamin C. Whether, as genetic engineering techniques become more refined in the future, it may become feasible to re-introduce this enzyme back into human cells, must remain a subject beyond the scope of this book, however fascinating and intriguing an idea.
Preparations of Vitamin C are frequently obtainable as salts of ascorbic acid, commonly as sodium or calcium ascorbate. Sodium (calcium) ascorbate is prepared from ascorbic acid and sodium (calcium) carbonate by controlled precipitation in dilute acetone or alcohol(184). Ester-CR ascorbate, prepared totally in aqueous solutions, has not, therefore, been exposed to these toxic chemicals.The more neutral pH and buffering power of ascorbate salts compared with ascorbic acid is frequently cited as a superior attribute of ascorbate products; the heatedly debated controversy recommending ascorbate salts over ascorbic acid and vice versa, and the advantages and claims of each of these products will be addressed in Chapter 11.
This may be the magic potentizers in Vitamin C research today and in the near future. Metabolites refer to substances or constituents which form part or take part in the metabolism of a substance. Other terms could be by-products, biochemical intermediates – ie, intermediate products in Vitamin C metabolism. Although Vitamin C research has been going on for over 4 decades, we are still at the infant stage in really unravelling exactly how Vitamin C gets absorbed and metabolized at the cellular level. The study of Vitamin C's metabolites may be crucial to shedding light at some of these crucial biochemical questions, which may lead to profound and perhaps powerful breakthroughs in several areas of medical science. The metabolism of Vitamin C into its constituent metabolites is shown here (Fig. 3):
The form of Vitamin C sold under Tradename Ester-RC refers to a composition of Vitamin C, normally an ascorbate salt, which also contains at least one of Vitamin C's naturally-occurring metabolites, ie one of the aldono-lactones or edible salts of l-threonic, l-xylonic and l-lyxonic acids(146). The manufacturing process of Ester-CR ascorbate is unique in that all reactions are carried out with aqueous solutions (water) and there is no use of organic solvents (acetone, alcohol) as in previous methods of ascorbate precipitation. The presence in significant quantities of metabolites in Ester-CR accounts for superior absorption and retention properties compared to ascorbic acid and ascorbates(229).